The olfactory and vomeronasal systems are two of several nasal chemoreceptive systems present in terrestrial vertebrates. The are major sources of direct exteroceptive information to the limbic system and have been implicated in a number of species-typical behaviors. Information to the brain via the olfactory and vomeronasal systems is important in virtually all vertebrates for appropriate endocrine, appetitive, social and secular response to chemosensory signals. Several issues concerning nasal chemical senses are addressed, including the nature of the adequate stimuli for activating the vomeronasal system, the molecular and cellular basis of stimulus transduction in the vomeronasal system, and the roles of central neural structures in responsiveness to prey chemicals. We are using snakes to study the vomeronasal and olfactory systems and the interactions between these two systems because snakes have extraordinarily well developed vomeronasal systems that are of critical importance in naturally occurring behaviors, such as courtship, prey discrimination and aggregation. Parallel work in other laboratories using mammals has demonstrated the applicability and generality of our findings to other vertebrates. A number of proteins from prey of garter snakes have been isolated. Purified and characterized and their potency tested behavioral and electrophysiologically. We propose to extend this work by identifying and characterizing the specific receptors for prey- derived chemoattractive proteins, identifying the second-messenger pathway(s) used in signal transduction and using molecular biological approaches to identify components in the signal transduction process. The roles of central nervous system components of the olfactory and vomeronasal systems in responding to prey chemical will be investigated by determining the effects of various lesions on discriminated response to prey chemicals. The sites of these lesions will be the terminations of mitral cell axons from the main and accessory olfactory bulb neurons, and their further projections.